Young Performance

Smitty,
No problem. Like I said, this is the first time that I used this dyno and was unaware when I first talked to the shop owner that all of the parameters were wrong. I found out after the first pull. I'm not trying to prove anything to anyone, just wanted to expose some members here to what I build. I have nothing to hide, and will gladely share all relevant info. I have built plenty motors with the same exact combo and know within 15 hp what they should make.
These motors were built for a very good friend of mine who happens to live about 2 blocks away. I can't hide from him, so everything has to be right.(not that I hide from anyone) The boat they are going in has had several sets of motors, including 500hp Mercs, 468 blower motors etc. He knows what the boat should run with X amount of power. If the motors don't make the power, he will know. I don't tune my motors for max hp. I don't even really care what they make. Most people are only concerned with a big hp number, which means nothing to me. I am looking for the best all around package. These motors were tuned for the boat, not the dyno, so they could have made a little more. When all the tuning is done, they make what they make.
Sorry if I sounded like an a-hole. I am very passionate about what I do, and put everything into each and every motor. This is all that I have ever wanted to do, and am glad that I have the chance to do it. Maybe we will get the chance to meet some day. Sounds like we have a lot in common, we both love hp. Thanks, Eddie.

Michael1

The J607 standard is not just different "due to a compensation for motoring friction loss". It is different because the standard pressures and temperatures are in the direction of greater horsepower. The equation for compensation IS different between the two standards, which affects the rate of change from the standard pressures and temperatures of each.

Correction factors are a compromise, and SAE specifies that no more than +/-7% correction be used. Correction factors assume a fixed motoring loss as a percentage of horsepower, which is not particularly accurate.

The aftermarket engine builders love J607, because it inflates their horsepower numbers over stock engines tested under J1349.

Michael

mike11

No scamming here smitty just building horsepower.

nordic95

WHERE??? JUST GO AWAY Mike you had to ruin it,here were a couple of guys who know what they are talking about having an intelligent conversation about some thing you know nothing about and you have to try and defend yourself. GO AWAY


Nordic95

articfriends

If you make it over here sometime for a few days let me know,I'm nestled in the country between vassar and reese,Smitty

bobl

I have a question. What happens to the dyno shops that are located at high altitude? The current absolute barometric pressure at denver is 24.77. According to my dyno tables that would result in 18% correction factor for the pressure alone. I'm at 1100' and most of my testing is at temperatures over 90 degrees ambient, plus humidity. My correction factors run around 6% on any given day.

SB

If they built + shipped you an engine that made similar power (up there) to yours (down here), you'd probably put holes in the pistons pretty quick.

Or if you sent them your engine you built it would be a major dog.

Say you where to build a pump gas engine at sea level that would be killer at their altitude - how would you test it + dyno it with pump gas and sea level tune ?

My honest opinion is that it would have to be sent there and tested unless you can somehow make your atmospheric conditions the same as their's.

What I'm getting at is that they'd be very different engine builds.

Or if one was built at one place and going to the other it would need to be tested in the same atmosphere.

BTW: I'm brainstorming and never really looked into this much other than some quick thoughts.

bobl

My question is concerning the dyno and correction factors. You're absolutely correct on the build issues. Let's assume a stock 502 Mag. It should run without changes at both altitudes, obviously with a much lower power output at 5000'. Now let's suppose I were to put that engine on a dyno up there. If you were to limit the correction factor to the noted 7% maximum as rmbuilder eluded to, it would not make near the corrected HP it is rated at, although it would at sea level. The reason for the correction is to standardize testing to compensate for atmospheric differences and friction losses. It is rather obvious that a larger correction than 7% is required in testing in a situation like this. So, going on rmbuilders statement:

"the SAE clearly states that if correction factors in excess of 7% occur during the testing, the results are invalid and the input criteria must be brought to within accepted parameters. Simply put, valid dynamometer testing is not conducted under any conditions cited above."

It appears one can not get valid dyno testing done in places such as Denver, Salt Lake city and so forth.

I'm certainly not doubting/disputing what was said. Just trying to gain (accurate) knowledge, and share what limited knowledge I have.

Bob

bobl

OK, I think I answered my own question. It's not that a correction of greater than 7% is invalid, but that SAE does not recognize it as acceptable. Therefore any testing that must be certified, such as a manufacture, is required to conduct those tests in an environment that meets this standard. I guess GM doesn't do there testing in Denver..LOL

SB

Nor would they want to in some 7.8:1 454. LOL !!!!

My scrambled thoughts above where mearly pointing out/discussing that the differences in air is so great, that it really doesn't make the engines comparable especially when building one to perform well in one of the altitudes.

I get calls all the time from CO people complaining about the power from their old GM trucks. I wonder why ? Maybe because they are dogs even at sea level maybe ? LOL.

The OE's do test at high altitude for programming reasons.